Usernames aren't limited to ASCII, as you can also register Chinese usernames (for instance, try 你好 ). I suppose it's possible to register usernames containing emoji unicode characters (). However, these usernames cannot be registered. The form disallows the use of these characters, and maybe there are also server-sided checks. In order to allow these characters, removing the checks (unsafe) or adding emoji characters to the checks (safe) from the source code would suffice.

But keep in mind that the character is different than , as the first one is unicode and the second one an image. Whatever emoji you want to use, it will have a unicode equivalent.

Usernames aren't limited to ASCII, as you can also register Chinese usernames (for instance, try 你好 ). I suppose it's possible to register usernames containing emoji unicode characters (). However, these usernames cannot be registered. The form disallows the use of these characters, and maybe there are also server-sided checks. In order to allow these characters, removing the checks (unsafe) or adding emoji characters to the checks (safe) from the source code would suffice.

But keep in mind that the character is different than , as the first one is unicode and the second one an image. Whatever emoji you want to use, it will have a unicode equivalent.

The function you will need to tweak is validateUsername. The problem with unicode emoji appears to be that utils.slugify does not seem to allow those characters. I think it's best to start with tweaking utils.slugify. You can find that in this file, line 77.https://github.com/NodeBB/NodeBB/blob/master/public/src/utils.js